1. Field of the Invention
The present invention relates to communication terminal devices and control methods thereof.
2. Related Background Art
Video conference systems based on personal computers have already been marketed. For example, Japanese Patent Application (Laid-Open) Nos. 9-200722 and 10-42178 by the applicant same as the assignee of the present application disclose such a system, which comprises a CODEC (coder and decoder) board and an ISDN (integrated services digital network) board each inserted in an extension slot of a computer, and a camera with a pan head, and includes software that operates on the computer. In such the conventional art, a monitor screen displays an operation panel as well as an image obtained through a camera. A user can control the camera operation such as panning, tilting, zooming, and focusing by manipulating a mouse and a keyboard attached to the computer. This type of video conference system based on personal computer is called DVC (desktop video conference system) type.
On the other hand, there are video conference systems that operate standalone with no computer. For example, such systems are available from Polycom as ViewStation (TM) and from PictureTel as SwiftSite II (TM). These systems are each operated through a remote controller and an image is displayed on a TV screen. The remote controller is provided with upward, downward, leftward, and rightward direction keys, a set key, a cancel key, and a menu key as its main functional keys, and additionally with a shortcut key. This type of video conference system is called STB (set top box) type because its main controller is set on a TV receiver in most cases.
Conventional DVC type video conference terminal devices have the following problems. In DVC type, installation of hardware and software into a personal computer is troublesome and highly expert knowledge of personal computer is required. Compatibility with a display card installed in the computer may come into question. Besides, even when a user wants to use the device soon, the computer must be powered first. The user must wait for start-up of the operating system and further for start-up of the dedicated application software. It requires a considerably long time.
On the other hand, STB type video conference terminal devices that operate standalone have the following problems. First, since a remote controller is used as the main control system of each device, it is unsuitable for complicated input operation. Particularly in case of making a telephone directory with Chinese characters and so on being input, the operation becomes complicated and troublesome. That is, the operability of the input means is bad. Secondly, since a remote controller is used as the main control system of each device, when two or more video conference terminal devices are close to one another, they may operate at once in response to a control signal from one remote controller and thereby be thrown into confusion. Thirdly, since a TV monitor is generally used for the display of each device, its display performance such as resolution is apt to be insufficient. In particular, a font larger than a certain size must be used for displaying a reproduced Chinese character or the like. If not so, the displayed character may be influenced by a flicker or have a blur on its profile, whereby it becomes hard to read. Fourthly, since the recording capacity of data is hard to be increased, in case of adding a static image capture function, an animation recording function, or the like, the number of images to be recorded, the recording time, or the like is apt to be limited. That is, there is a certain limit of storage capacity.